Question 1

Which of the following best explains why hemoglobin releases more oxygen in metabolically active tissues?

Accepted Answer

Because increased temperature and decreased pH shift the oxygen-hemoglobin dissociation curve to the right, decreasing hemoglobin's affinity for oxygen.

Question 2

A patient is experiencing cyanosis due to hypoxia. Which type of hypoxia is most likely if the patient has normal blood flow but is exposed to cyanide?

Accepted Answer

Histotoxic hypoxia

Question 3

Which equation correctly represents the reversible reaction catalyzed by carbonic anhydrase in red blood cells?

Accepted Answer

$$CO_2 + H_2O$$ \rightleftharpoons H_2CO_3 \rightleftharpoons $$HCO_3^- + H$$^+$$

Question 4

During exercise, ventilation increases abruptly at the start. Which mechanism is LEAST likely to contribute to this initial increase?

Accepted Answer

Sudden rise in arterial $$P_{CO_2$}$$

Question 5

Which of the following statements about the oxygen-hemoglobin dissociation curve is correct?

Accepted Answer

It is S-shaped, reflecting cooperative binding of oxygen to hemoglobin.

Question 6

A swimmer hyperventilates before a long dive. What is the physiological risk associated with this practice?

Accepted Answer

Decreased $$P_{CO_2$}$$ delays the urge to breathe, risking dangerous drops in $$P_{O_2$}$$ and possible blackout.

Question 7

Which form of carbon dioxide transport in blood accounts for the largest percentage?

Accepted Answer

As bicarbonate ions ($$HCO_3$$^-$$) in plasma

Question 8

What is the Haldane effect?

Accepted Answer

The increased ability of deoxygenated hemoglobin to bind $$CO_2$$ and buffer $$H^+$$ ions.

Question 9

Which of the following would most likely result in respiratory alkalosis?

Accepted Answer

Rapid, deep breathing causing decreased $$CO_2 in $$blood

Question 10

Which neural group is primarily responsible for setting the basic rhythm of breathing?

Accepted Answer

Ventral respiratory group (VRG)

Question 11

A patient with chronic obstructive pulmonary disease (COPD) is likely to experience which of the following symptoms due to decreased lung elasticity?

Accepted Answer

Hyperinflation of the chest and increased energy expenditure for breathing

Question 12

Which of the following is TRUE regarding the Bohr effect?

Accepted Answer

Increased $$CO_2$$ and decreased pH cause hemoglobin to release more oxygen.

Question 13

Which of the following best describes the chloride shift in systemic capillaries?

Accepted Answer

Chloride ions move into RBCs as bicarbonate ions exit into plasma.

Question 14

Which chemical factor is the most potent and closely controlled in regulating breathing rate and depth?

Accepted Answer

$$P_{CO_2$}$$

Question 15

A person at high altitude experiences increased ventilation over several days. Which physiological change is most responsible for this acclimatization?

Accepted Answer

Increased sensitivity of peripheral chemoreceptors to $$O_2$$

Question 16

Which of the following is a major stimulus for respiration when arterial $$P_{O_2$}$$ falls below 60 mm Hg?

Accepted Answer

Peripheral chemoreceptors

Question 17

Which of the following lung diseases is characterized by permanent enlargement and destruction of alveolar walls, leading to decreased lung elasticity?

Accepted Answer

Emphysema

Question 18

Which of the following is the correct formula for the reaction of $$CO_2$$ with hemoglobin to form carbaminohemoglobin?

Accepted Answer

$$CO_2 + Hb$$ \rightarrow $$HbCO_2$$

Question 19

Which of the following is a direct effect of rapid, deep breathing (hyperventilation) on blood pH?

Accepted Answer

Increase in blood pH due to decreased $$CO_2$$

Transport of Respiratory Gases and Control of Respiration

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